Liquid crystal display device and manufacturing method for the same

ABSTRACT

On a glass substrate, gate bus lines, data bus lines, and TFTs are formed. Then, on the substrate, an insulating film, covering the gate bus lines, data bus lines and TFTs, is formed, and a positive type photoresist film is further formed thereon. Next, through exposure and development processes, the resist film is divided for each picture element and subjected to ultraviolet ray irradiation to harden only a surface layer thereof. Then, the resist film is subjected to heat treatment to form thereon wrinkle-form surface ruggedness of a uniform pattern, which is determined depending on the size of the resist film. Subsequently, reflection electrodes are formed on the resist film. The reflection electrodes are formed to overlap the gate bus line, data bus line and TFTs, and the regions between the adjacent reflection electrodes serve as light transmission regions.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims priority of JapanesePatent Applications No. 2002-347077, filed on Nov. 29, 2002, and No.2002-323073, filed on Nov. 6, 2002, the contents being incorporatedherein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a liquid crystal display devicehaving a reflection electrode and a manufacturing method for the sameand, more particularly, to a liquid crystal display device applicable toa transflective type liquid crystal display device which can be used asa reflection type liquid crystal display device in the environment of abright ambient, and can be used as a transmission type liquid crystaldisplay device by switching on a backlight in the environment of a darkambient, and a manufacturing method for the same.

[0004] 2. Description of the Prior Art

[0005] A liquid crystal display device is thin and lightweight comparedwith a CRT (Cathode Ray Tube), having an advantage that it can be drivenwith a lower voltage with low power consumption. The liquid crystaldisplay device is used for various electronic devices such as a TV set,a notebook type personal computer, a desktop type personal computer, aPDA (Personal Digital Assistance), and a cellular telephone. Especially,an active matrix type liquid crystal display device provided with a TFT(Thin-film transistor) as a switching element for each sub-pixel(hereafter, referred to as a picture element in this invention) shows anexcellent display characteristic comparable to the CRT, with its highdriving capability. Therefore, the active matrix type liquid crystaldisplay device has been extensively used for the fields whereconventionally the CRT is used, such as a desktop type personal computerand a TV set.

[0006] Generally, the liquid crystal display device has a structure inwhich liquid crystal is enclosed between two transparent substrates. Apicture element electrode, the TFT and the like are formed for eachpicture element on one of the two transparent substrates, and colorfilters disposed opposingly to the picture element electrode and acommon electrode that is common to each picture element are formed onthe other substrate. Hereafter, the substrate having the picture elementelectrode and the TFT formed thereon is referred to as a TFT substrate,and the substrate arranged opposingly to the TFT substrate is referredto as a counter substrate. Note that one pixel is formed of threepicture elements (sub-pixels) of red (R), green (G) and blue (B).

[0007] The liquid crystal display device includes a transmission typeliquid crystal display device and a reflection type liquid crystaldisplay device. The transmission type liquid crystal display devicedisplays images by controlling the light quantity of transmitted rays oflight for each picture element, while the reflection type liquid crystaldisplay device displays images by controlling the light quantity ofreflected rays of light for each picture element. The transmission typeliquid crystal display device requires an exclusive light source calleda backlight. Meanwhile, in the reflection type liquid crystal displaydevice, an ambient condition of light (natural light or lamplight) isused as a light source. Therefore, the reflection type liquid crystaldisplay device has a merit of consuming much less power compared withthe transmission type liquid crystal display device. In addition, thereflection type liquid crystal display device is more excellent invisibility outdoors than the transmission type liquid crystal displaydevice. Hereafter, the picture element electrode of the reflection typeliquid crystal display device is also referred to as a reflectionelectrode.

[0008] For example, Japanese Patent Laid-Open No. Hei 08-338993discloses a reflection type liquid crystal display device in which a TN(twisted nematic) type liquid crystal is used and an alignment film issubjected to rubbing treatment to make the liquid crystal twist align.Moreover, Japanese Patent Laid-Open No. Hei 05-232465 discloses a liquidcrystal display device whose reflection electrode is provided withruggedness by using a photolithography method. In this way, by providingthe surface of the reflection electrode with ruggedness, it is avoidedthat the visibility is greatly changed depending on a position where apanel is observed, by irregular reflection of light.

[0009] However, the process for forming ruggedness on the surface of thereflection electrode is complicated in the above-described method.Hereupon, the present inventors provide a method for forming areflection electrode provided with ruggedness on the surface thereof byusing a positive type photoresist (for example, Japanese PatentLaid-Opens No. 2002-221716 and No. 2002-296585). In this method, thestep to harden only a surface layer is carried out by subjecting thephotoresist to ultraviolet ray irradiation and followed by heattreatment. Fine ruggedness is thus formed on the surface of the resistfilm. Then, by forming the reflection electrode on the resist film, thereflection electrode having surface ruggedness can be easily formed.

[0010] Incidentally, in the reflection type liquid crystal displaydevice, since an ambient condition of light (natural light or lamplight)is used as a light source, the visibility is greatly changed dependingon the ambient condition of light. That is, when its neighborhood isbright, the visibility of the reflection type liquid crystal displaydevice is satisfactory. However, when its neighborhood is dark, thevisibility thereof is extremely decreased. In order to overcome such adisadvantage, the reflection type liquid crystal display device having alight source (front light unit) on a front panel surface, is proposed.However, the reflection type liquid crystal display device with thisstructure is formed so that the light reflected by the reflectionelectrode may be transmitted through the front light unit, where thereflective light is reduced. Therefore, such a reflection type liquidcrystal display device poses a problem that contrast of an image islowered and sufficient visibility is not obtained compared with thereflection type liquid crystal display device without any front lightunit.

[0011] Japanese Patent Laid-Open No. Hei 07-333598 discloses a liquidcrystal display device (hereafter, referred to as a transflective typeliquid crystal display device) that can be used as a reflection typeliquid crystal display device when its neighborhood is bright, and as atransmission type liquid crystal display device by switching on abacklight when its neighborhood is dark. This is realized by forming areflection electrode of a metal thin film for semi-transmitting light.However, in this type of transflective type liquid crystal displaydevice, when used as a transmission type liquid crystal display device,light absorption by the metal thin film is increased. Therefore, theutilization efficiency of light is bad, involving a problem thatsatisfactory visibility cannot be obtained unless a backlight havinglarge luminance is used. Al (aluminum) film having a thickness of about30 nm is used as the metal thin film for semi-transmitting light.However, in the case of a large-sized liquid crystal display device, itis extremely difficult to form an Al thin film having a uniformthickness over the entire surface of a panel.

[0012] Japanese Patent Laid-Open No. Hei 11-281972 discloses atransflective type liquid crystal display device in which the centralpart of a reflection electrode is opened to form a transmission regionthrough which light is transmitted, and in the transmission region, atransparent electrode such as an ITO (Indium-Tin Oxide) is formed.

[0013]FIG. 1 is a schematic diagram showing an example of the TFTsubstrate of a conventional transflective type liquid crystal displaydevice with the above structure.

[0014] On the TFT substrate, a plurality of gate bus lines 71 disposedso as to be parallel to each other, and a plurality of data bus lines 72so as to be orthogonal to the gate bus lines 71, are formed. In thevicinity of each area where the gate bus line 71 and the data bus line72 intersect with each other, a TFT 73 is formed. Moreover, in eachrectangular region partitioned by the gate bus lines 71 and the data buslines 72, a reflection electrode 74 made of a metal film for reflectinglight such as Al (aluminum) is formed. In the central part of thereflection electrode 74, an opening part 74 a for transmitting light isformed, and in the opening part 74 a, a transparent electrode 75 made ofa transparent electric conductor such as ITO is formed.

[0015] The gate bus lines 71, the data bus lines 72, and the TFTs 73 arecovered with an insulating flattening film; the reflection electrodes 74are formed on the flattening film; and the transparent electrodes 75 areformed under the flattening film. When direct contact of the Alconstituting the reflection electrodes 74 and the ITO constituting thetransparent electrodes 75 occurs, corrosion is caused due to a batteryeffect. For this reason, the reflection electrodes 74 and thetransparent electrodes 75 are electrically connected via a barrier metalsuch as Ti (titanium).

[0016] In the liquid crystal display device with the above structure,scanning signals are sequentially supplied to a plurality of the gatebus lines 71, and display signals are supplied to each of the data buslines 72 when displaying an image. Then, the TFTs 73 connected to thegate bus lines 71 supplied with the scanning signals become in ONstates, and the display signals are written in the reflection electrodes74 and the transparent electrodes 75 via the TFTs 73, whereby theorientation of liquid crystal molecules between the reflectionelectrodes 74 and the counter substrate, as well as the transparentelectrodes 75 and the counter substrate, are changed. Consequently, thelight quantity of the reflective light or the transmitted light is alsochanged. By controlling the light quantity of the reflective light orthe transmitted light for each picture element, a desired image isdisplayed on the liquid crystal display device.

[0017] According to the transflective type liquid crystal displaydevice, comparatively satisfactory visibility is secured in any case ofusing it as the reflection type display device or as the transmissiontype display device.

[0018] However, in the transflective type liquid crystal display devicedisclosed in Japanese Patent Laid-Open No. Hei 11-281972, thetransparent electrodes made of ITO and the barrier metal are required tobe formed in addition to the reflection electrodes made of Al.Accordingly, there arises a problem that many processes are required,involving an increase in product costs.

[0019] Furthermore, in this transflective type liquid crystal displaydevice, if the transmission region is enlarged, the reflection region isreduced. Transmission and reflection characteristics are thus defined bya trade-off relation. In a liquid crystal display device with highresolution, the area of one picture element is small. Therefore, it isdifficult to obtain a satisfactory liquid crystal display device inreflection characteristics as well as in transmission characteristics.

[0020] Further, in the reflection region, incident light is transmittedthrough CF (color filter) layers two times and emitted to a displayscreen side. Meanwhile, in the transmission region, incident light istransmitted through the CF layers only once and emitted to the displayscreen side. For this reason, chromaticity irregularity is generatedbetween the cases of using the transflective type liquid crystal displaydevice as a reflection type liquid crystal display device (hereafter,referred to as a reflection mode) and as a transmission type liquidcrystal display device (hereafter, referred to as a transmission mode).

[0021] When the color purity of the CF layers is adjusted so that abright display can be obtained when displaying in the reflection mode,the color purity in the transmission mode is deteriorated, resulting ina display in light colors. Conversely, when the color purity of the CFlayers is adjusted so that satisfactory color rang can be obtained whendisplaying in the transmission mode, reflected light is lowered whendisplaying in the reflection mode, resulting in an extremely darkdisplay.

[0022] In order to overcome the above-described problems, a structure ofthe liquid crystal display device is conventionally known, in which thecolor purity of the CF layers is made to be different between thereflection regions and the transmission regions (for example, JapanesePatent Laid-Open No. Hei 11-2811). In this structure, for example, theCF layers are not formed in the reflection regions, but formed in thetransmission regions only. Accordingly, when displaying in thetransmission mode, a display with high color purity can be obtained, andwhen displaying in the reflection mode, a display with high luminance,in achromatic colors though, can be obtained. However, this structureinvolves a problem that display quality is greatly changed when thereflection mode and the transmission mode are switched with each other.Moreover, in the reflection mode, a full-color display cannot beprovided, involving a problem that a transmittable information quantityfor users via the display screen is reduced and good display qualitycannot be obtained.

[0023] In order to overcome the above-described problems, anotherstructure of the liquid crystal display device is conventionally known,in which color purity is made to be different between the reflectionregions and the transmission regions (for example, Japanese PatentLaid-Opens No. Hei 11-305248 and No. 2001-166289). However, in thisstructure, while the chromaticity irregularity between the transmissionmode and the reflection mode can be reduced, reflection characteristicsand transmission characteristics are still defined by a trade-offrelation. Therefore, it is difficult to improve both of the reflectioncharacteristics and the transmission characteristics, raising a problemthat utilization efficiency of light is degraded.

[0024] Also, there is provided a reflection type liquid crystal displaydevice in which the color purity of the CF layers is made to bedifferent for each picture element region (for example, Japanese PatentLaid-Open No. Hei 10-307205). In this structure, a display is producedusing picture elements of six colors in total including three colors ofred (R), green (G) and blue (B) with the addition of complementarycolors thereof of cyan (C), magenta (M) and yellow (Y), therebyenlarging the range for color reproduction. However, an increase in adrive circuit leads to an increase in the manufacturing costs, andtherefore the liquid crystal display device provided with the pictureelements of six colors may not be practical. In addition, the abovestructure is not applicable to the transflective type liquid crystaldisplay device.

[0025] The transflective type liquid crystal display device thatimproves the transmission characteristics without decreasing thereflection characteristics, is proposed in Japanese Patent Laid-Open No.2003-202594 filed by the present applicant. This transflective typeliquid crystal display device will be explained with reference to FIGS.2 to 5. FIG. 2 shows a structure of the TFT substrates of thetransflective type liquid crystal display device, and FIG. 3 shows asectional structure of the transflective type liquid crystal devicetaken along the line I-I of FIG. 2. As shown in FIGS. 2 and 3,reflection electrodes 110 are formed so as to cover gate bus lines 104,data bus lines 106, and TFTs 108. The regions where the reflectionelectrodes 110 are formed serve as reflection regions R and R′. Theregions surrounding the reflection electrodes 110 serve as transmissionregions T and T′. The liquid crystal in the transmission regions T andT′ are driven similarly to the liquid crystal in the reflection regionsR and R′ by an oblique electric field between the reflection electrodes110 and a common electrode 130.

[0026] In this structure, the regions used neither as the reflectionregions nor as the transmission regions in the conventional liquidcrystal display device, are used as the transmission regions T and T′.Moreover, the areas of the gate bus lines 104, the data bus lines 106,and the TFTs 108 which are exposed in the transmission regions T and T′,are decreased to a large extent. Therefore, the areas of thetransmission regions T and T′ can be enlarged without decreasing theareas of the reflection regions R and R′. Accordingly, the transmissioncharacteristics can be improved without decreasing the reflectioncharacteristics, and good display characteristics can be obtained inboth of the reflection mode and the transmission mode.

[0027]FIG. 4 shows another structure of the transflective type liquidcrystal display device. As shown in FIG. 4, the reflection electrodes110 are formed in regions surrounded by the gate bus lines 104 and thedata bus lines 106. The regions where the reflection electrodes 110 areformed serve as reflection regions. The reflection electrodes 110 haveopening parts 150 a to 150 e formed therein. The opening parts 150 a to150 e are opened to be formed into various shapes such as a slit-likeshape and a circular or polygonal hole-like shape. The regions where theopening parts 150 a to 150 e are formed serve as transmission regions.

[0028]FIG. 5 shows further another structure of the transflective typeliquid crystal display device. As shown in FIG. 5, the reflectionelectrodes 110 are formed so as to cover the gate bus lines 104, databus lines 106, and the TFTs 108. The regions where the reflectionelectrodes 110 are formed serve as reflection regions. The reflectionelectrodes 110 have opening parts 150 f to 150 k formed therein whichare opened to be formed into a slit-like shape, a circular or polygonalhole-like shape and the like. The regions where the opening parts 150 fto 150 k are formed and the regions between the adjacent reflectionelectrodes 110 serve as transmission regions.

[0029] In the structures shown in FIGS. 4 and 5, transparent electrodessuch as ITO are not formed in the transmission regions. Therefore, thetransparent electrodes and a barrier metal layer are not required to beformed therein. Moreover, for example, by forming the opening parts 150a to 150 k into a shape enabling the orientation control of a liquidcrystal having negative dielectric anisotropy, rubbing treatment for anoriented film can be eliminated. Accordingly, a manufacturing process ofthe liquid crystal display device is simplified and manufacturing costsare reduced.

[0030] As described above, according to the transflective type liquidcrystal display devices as shown in FIGS. 2 to 5, the transmissioncharacteristics can be enhanced without decreasing the reflectioncharacteristics. At the same time, the manufacturing process can besimplified and the manufacturing costs can be reduced. However, thistransflective type liquid crystal display device still has such problemsas will be described below. FIG. 6 shows a schematic sectional structureof three picture elements of the liquid crystal display device takenalong the line II-II of FIG. 4. As shown in FIG. 6, a light beam t ofthe transmission light emitted from a backlight unit (not shown) to beemitted to a display screen side, and a light beam r of the reflectionlight incident from the display screen side and reflected by thereflection electrode 110 to be emitted to the display screen side, passalong different light paths. That is, the light beam t of thetransmission light is transmitted through the CF layer R only once. Onthe other hand, the light beam r of the reflection light is transmittedthrough the CF layer R twice. Therefore, there arises a problem thatcolor purity is made to be different between the transmission modedisplay and the reflection mode display, thereby degrading displayquality.

[0031] Moreover, in order to obviate the occurrence of difference incolor purity between the transmission mode display and the reflectionmode display, it is conventionally known that the film thickness of theCF layers in the transmission regions is made twice as thick as CFlayers in the reflection regions. However, in this structure, alignmentmargins for tolerating alignment deviation generated when aligning a TFTsubstrate 102 having the reflection electrodes 110 formed thereon with acounter substrate 114 having the CF layers formed thereon, cannot besecured. For this reason, there arises a problem that when the alignmentdeviation is generated, color purity is made to be different between thetransmission mode display and the reflection mode display, therebydegrading the display quality.

SUMMARY OF THE INVENTION

[0032] An object of the present invention is to provide a liquid crystaldisplay device of those with high resolution, excellent in reflectioncharacteristics compared with a conventional one, and a manufacturingmethod for the same.

[0033] Another object of the present invention is to provide atransflective type liquid crystal display device which can bemanufactured more easily than a conventional one and is good inreflection characteristics and transmission characteristics, and amanufacturing method for the same.

[0034] Further another object of the present invention is to provide aliquid crystal display device having good display quality.

[0035] The above-described problems are solved by a liquid crystaldisplay device constituted by enclosing liquid crystal between a pair ofsubstrates. The liquid crystal display device includes, on one of thepair of substrates, gate bus lines supplied with scanning signals; databus lines supplied with display signals; thin-film transistors havinggate electrodes electrically connected to the gate bus lines and drainelectrodes electrically connected to the data bus lines; a resin filmdivided for each picture element and having wrinkle-form surfaceruggedness; reflection electrodes formed on the resin film, having finesurface ruggedness following the surface ruggedness of the resin film,and electrically connected to source electrodes of the thin-filmtransistors.

[0036] In the present invention, the resin film having the wrinkle-formrugged surface formed thereon is divided for each picture element. Asdisclosed in Japanese Patent Laid-Open No. 2002-221716, if the surfaceof a resin film is hardened, and followed by heat treatment, finewrinkle-form surface ruggedness can be formed. It is confirmed,according to experiments by the present inventors, that a wrinkle-formrugged pattern formed on the surface of the resist film is not uniformwhen the resist film is large in size, while a uniform wrinkle-formrugged pattern is formed in accordance with the size of the resist filmwhen the size of the resist film is reduced.

[0037] In order to obtain such an effect, a picture element ispreferably set to the size corresponding to 110 to 850 ppi (pixel perinch). When the size of a picture element is large, a slit is formed onthe resist film and the reflection electrode to divide the resist filmand the reflection electrode for one picture element into a plurality ofregions. The similar effects can be thus obtained. Accordingly, if thesizes of the resist film and the reflection electrode are determinedbeforehand and a rugged pattern is formed so that light incident to aliquid crystal panel from the upside may be reflected in the directionof a normal line of a panel surface, utilization efficiency of light isimproved and visibility is improved.

[0038] Note that in order to obtain good reflection characteristics, aflattened area where the average angle of the surface of the reflectionelectrode is 5° or less is preferably set to 50% or more. In addition,when the resist film is divided by the slit into the plurality ofregions, the length of the short side of each divided region ispreferably set to 5 μm or more in order to obtain surface ruggedness ofa uniform pattern on the resist film.

[0039] In addition, when the resist film and the reflection electrodesare formed so that the gate bus lines, data bus lines, and the thin-filmtransistors may be overlapped one another, the regions between theadjacent reflection electrodes can be set as light transmission regionsthrough which light is transmitted, thereby realizing the transflectivetype liquid crystal display device. In this case, liquid crystalmolecules in the light transmission regions are driven by an electricfield transversely leaked from the reflection electrodes.

[0040] The above-described problems are solved by a liquid crystaldisplay device constituted by enclosing liquid crystal between a pair ofsubstrates, including, on one of the pair of substrates, gate bus linessupplied with scanning signals; data bus lines supplied with displaysignals; thin-film transistors having gate electrodes and drainelectrodes, the gate electrodes being electrically connected to the gatebus lines and the drain electrodes being electrically connected to thedata bus lines; a resin film divided for each picture element anddisposed on upper part of the gate bus lines, the data bus lines, andthe thin-film transistors; and reflection electrodes formed on the resinfilm and electrically connected to source electrodes of the thin-filmtransistors.

[0041] In the present invention, the resin film, which is divided foreach picture element, and the reflection electrodes are formed so as tooverlap the gate bus lines, data bus lines, and thin-film transistors.In this case, the regions between the adjacent reflection electrodesserve as light transmission regions through which light is transmitted.Accordingly, compared with a method of creating the light transmissionregions by forming opening parts in the reflection electrodes, the areasof the light transmission regions can be increased even though the areasof the reflection electrodes are the same.

[0042] The above problems are solved by a manufacturing method for aliquid crystal display device including the steps of: forming on a firstsubstrate gate bus lines supplied with scanning signals, data bus linessupplied with display signals, and thin-film transistors having gateelectrodes connected to the gate bus line and drain electrodes connectedto the data bus line; forming a photoresist film on upper part of thegate bus lines, the data bus lines, and the thin-film transistors;dividing the photoresist film for each picture element, and exposing anddeveloping photoresist to form opening parts at positions correspondingto source electrodes of the thin-film transistors; hardening only asurface layer of the photoresist film; subjecting the photoresist filmto heat treatment to form wrinkle-form surface ruggedness; forming onthe photoresist film reflection electrodes electrically connected to thesource electrodes of the thin-film transistors via the opening parts;and arranging opposingly the first substrate and a second substrateprovided with an electrode made of a transparent conductive film, andenclosing liquid crystal therebetween.

[0043] According to the present invention, the photoresist film isdivided for each picture element and followed by heat treatment, therebyforming surface ruggedness. In this case, it is confirmed in experimentsby the present inventors that a uniform rugged pattern can be formed inaccordance with the size of the photoresist film. Therefore, whileconsidering conditions of actually using the liquid crystal displaydevice, if the size of the resist film is set, to form a rugged pattern,so that light incident to a liquid crystal panel from the upside can bereflected in the direction of a normal line of a panel surface,utilization efficiency of light is improved and visibility is improved.

[0044] The above-described problems are solved by a manufacturing methodfor the liquid crystal display device, including the steps of: formingon a first substrate gate bus lines supplied with scanning signals, databus lines supplied with display signals, and thin-film transistorshaving gate electrodes connected to the gate bus lines and drainelectrodes connected to the data bus lines; forming a photoresist filmon upper part of the gate bus lines, the data bus lines, and thethin-film transistors; dividing the photoresist film for each reflectionelectrode forming region overlapping with the gate bus line, the databus line and the thin-film transistor, and exposing and developingphotoresist to form opening parts at positions corresponding to sourceelectrodes of the thin-film transistors; forming on the photoresist filmreflection electrodes electrically connected to the source electrodes ofthe thin-film transistors via the opening parts; and arrangingopposingly the first substrate and a second substrate provided with anelectrode made of a transparent conductive film, and enclosing liquidcrystal therebetween.

[0045] In the present invention, the resist film and the reflectionelectrodes are divided for each picture element so as to overlap thegate bus lines, data bus lines, and the thin-film transistors. In thiscase, the regions between the adjacent reflection electrodes serve aslight transmission regions through which light is transmitted. Comparedwith a method of creating the light transmission regions by formingopening parts in the reflection electrodes, the areas of the lighttransmission regions can be increased even though the areas of thereflection electrodes are the same.

[0046] The above-described problems are solved by a liquid crystaldisplay device including: a pair of substrates opposingly arranged; aliquid crystal enclosed between the pair of substrates; a plurality ofpicture element regions, each including a reflection region having areflection electrode formed on one of the pair of substrates andreflecting light incident from the other substrate, and a transmissionregion for transmitting light incident from the one substrate, thetransmission region being a region of a circumference or an opening partof the reflection electrode; and wavelength selecting layers, eachformed in the transmission region, extending up to part of thereflection region, and selecting and transmitting light having apredetermined wavelength.

[0047] In the present invention, the wavelength selecting layers extendup to part of the reflection regions, and therefore when displaying inthe reflection mode, the light that is transmitted though the wavelengthselecting layers twice and the light that is not transmitted through thereflection selecting layers are mixed, thereby providing a highluminance display. Moreover, the area ratio of the regions for formingthe wavelength selecting layers of the reflection regions to the entirereflection regions is adjusted, thereby making the color purity of thereflection mode display closer to the color purity of the transmissionmode display. Thus, the transflective type liquid crystal display devicewith good display quality can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

[0048]FIG. 1 is a schematic diagram showing an example of a TFTsubstrate of a conventional transflective type liquid crystal displaydevice.

[0049]FIG. 2 is a plan view showing a structure of another conventionaltransflective type liquid crystal display device.

[0050]FIG. 3 is a sectional view taken along the line I-I of FIG. 2.

[0051]FIG. 4 is a plan view showing a structure of further anotherconventional transflective type liquid crystal display device.

[0052]FIG. 5 is a plan view showing a structure of still anotherconventional transflective type liquid crystal display device.

[0053]FIG. 6 is a sectional view explaining about a problem of aconventional liquid crystal display device.

[0054]FIG. 7 is a plan view showing a liquid crystal display deviceaccording to a first embodiment of the present invention.

[0055]FIG. 8 is a schematic sectional view taken along the line III-IIIof FIG. 7.

[0056]FIGS. 9A to 9M are schematic sectional views showing amanufacturing method for a TFT substrate of the liquid crystal displaydevice according to the first embodiment of the present invention in aprocess order.

[0057]FIG. 10 is a view showing relations of transmissive aperture ratioand effective reflection area ratio to resolution, between aconventional transflective type liquid crystal display device and thetransflective type liquid crystal display device of the firstembodiment.

[0058]FIG. 11 is a view showing microscopic images obtained by checkinga reflection state and a transmission state when applied voltages are 0Vand 2.3 V, in the liquid crystal display device manufactured accordingto the first embodiment.

[0059]FIG. 12 is a view showing an AFM image of a reflection electrodeof the liquid crystal display device according to the first embodiment.

[0060]FIGS. 13A to 13C are plan views showing a transflective typeliquid crystal display device according to a second embodiment of thepresent invention.

[0061]FIG. 14 is a view showing relations of transmissive aperture ratioand effective reflection area ratio to resolution, between aconventional transflective type liquid crystal display device and thetransflective type liquid crystal display device of the secondembodiment.

[0062]FIG. 15 is a view showing microscopic images obtained by checkinga display state when applied voltages are 0V and 2.3 V, in the liquidcrystal display device manufactured according to the second embodiment.

[0063]FIGS. 16A to 16C are plan views showing a transflective typeliquid crystal display device according to a third embodiment of thepresent invention.

[0064]FIG. 17 is a view showing microscopic images obtained by checkinga display state when applied voltages are 0V and 2.3 V, in the liquidcrystal display device manufactured according to the third embodiment.

[0065]FIG. 18 is an outline structure of a liquid crystal display deviceaccording to a first basic structure of a fourth embodiment of thepresent invention.

[0066]FIG. 19 is a sectional view showing a schematic structure of theliquid crystal display device according to the first basic structure ofthe fourth embodiment of the present invention.

[0067]FIG. 20 is a sectional view showing a schematic structure of aliquid crystal display device according to a second basic structure ofthe fourth embodiment of the present invention.

[0068]FIGS. 21A and 21B are sectional views showing a schematicstructure of a liquid crystal display device according to a third basicstructure of the fourth embodiment of the present invention.

[0069]FIGS. 22A and 22B are sectional views showing schematic structuresof a liquid crystal display device according to a fourth basic structureof the fourth embodiment of the present invention.

[0070]FIG. 23 is a sectional view showing a schematic structure of theliquid crystal display device according to the fourth basic structure ofthe fourth embodiment of the present invention.

[0071]FIGS. 24A and 24B are views showing a structure of a liquidcrystal display device according to example 1 of the fourth embodimentof the present invention.

[0072]FIG. 25 is an x-y chromaticity chart of the liquid crystal displaydevice according to example 1 of the fourth embodiment of the presentinvention.

[0073]FIGS. 26A and 26B are views showing a structure of a liquidcrystal display device according to example 2 of the fourth embodimentof the present invention.

[0074]FIGS. 27A and 27B are views showing a structure of a liquidcrystal display device according to example 3 of the fourth embodimentof the present invention.

[0075]FIGS. 28A and 28B are views showing a structure of a liquidcrystal display device according to example 4 of the fourth embodimentof the present invention.

[0076]FIG. 29 is a view showing a structure of a liquid crystal displaydevice according to a fifth embodiment of the present invention.

[0077]FIG. 30 is a view showing a modified example of the structure ofthe liquid crystal display device according to the fifth embodiment ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0078] Hereafter, preferred embodiments of the present invention will beexplained with reference to the accompanying drawings.

First Embodiment

[0079]FIG. 7 is a plan view showing a liquid crystal display device of afirst embodiment of the present invention, and FIG. 8 is a schematicsectional view taken along the line III-III of FIG. 7. Note that thisembodiment shows an example in which the present invention is applied toa transflective type liquid crystal display device using a VA(vertically aligned) type liquid crystal.

[0080] As shown in FIG. 8, the liquid crystal display device of thisembodiment is constituted including a TFT substrate 10 and a countersubstrate 30, and a vertically aligned nematic liquid crystal 40. TheTFT substrate 10 and the counter substrate 30 face each other, and thevertically aligned nematic liquid crystal 40 is enclosed between thesesubstrates. Polarizing plates (linear polarizing plate or circularpolarizing plate having the linear polarized light+λ/4 phase differencecombined) 38 and 39 are arranged under the TFT substrate 10 and on thecounter substrate 30, respectively. In addition, a light source(backlight: not shown) is disposed below the TFT substrate 10.

[0081] As shown in FIGS. 7 and 8, the TFT substrate 10 is constitutedincluding a glass substrate 11, gate bus lines 12 a formed on the glasssubstrate 11, storage capacitor bus lines 12 b, data bus lines 17 a,storage capacitor electrodes 17 b, TFTs 7 and reflection electrodes 20 aand the like. The gate bus lines 12 a and the storage capacitor buslines 12 b horizontally extend, and the data bus lines 17 a verticallyextend. The gate bus lines 12 a and the storage capacitor bus lines 12 bare covered with a gate insulating film 13 and electrically disconnectedfrom the data bus lines 17 a by this gate insulating film 13.

[0082] In the vicinity of each portion where the gate bus line 12 a andthe data bus line 17 a intersect with each other, the TFT 7 is formed.This TFT 7 is constituted by using a silicon film (amorphous siliconfilm or polysilicon film) 14 formed on the gate insulating film 13 as anoperating layer, and using part of the gate bus line 12 a as a gateelectrode. A channel protection film 15 a made of SiN is formed on thechannel region of this TFT 7. A drain electrode 17 d and a sourceelectrode 17 s are respectively formed on both sides of the channelprotection film 15 a. These drain electrode 17 d and source electrode 17s are electrically connected to the silicon film 14 via an n⁺ typeamorphous silicon film 16, which is an ohmic contact layer. Moreover,the drain electrode 17 d is electrically connected to the data bus line17 a, and the source electrode 17 s is electrically connected to thereflection electrode 20 a.

[0083] Further, the storage capacitor electrodes 17 b are formed abovethe storage capacitor bus lines 12 b via the gate insulating film 13.

[0084] The TFTs 7 and the storage capacitor electrodes 17 b are coveredwith a final protection film (not shown) made of SiN or the like, and aresist film 19 having a finely rugged surface is formed thereon. Thereflection electrodes 20 a made of Al or the like are formed on theresist film 19. The reflection electrode 20 a is electrically connectedto the source electrode 17 s of the TFT 7 and the storage capacitorelectrode 17 b via contact holes 18 a and 18 b formed on the finalprotection film and the resist film 19. Moreover, a rugged patternfollowing that of the resist film 19 is formed on the surface of thereflection electrode 20 a.

[0085] In this embodiment, the resist film 19 is formed only below thereflection electrode 20 a. In addition, the resolution of the liquidcrystal display device of this embodiment is 110 to 850 ppi, and thesize of the reflection electrode 20 a is set according to theresolution. Further, in this embodiment, as shown in FIG. 7, thereflection electrode 20 a is formed so as to overlap the gate bus line12 a, the storage capacitor bus line 12 b, the data bus line 17 a andthe TFT 7, and the region between the adjacent reflection electrodes 20a serves as a transmission region through which light is transmitted isformed.

[0086] An alignment layer 21 made of polyimide or the like is formed onthe reflection electrode 20 a. In this embodiment, the surface of thealignment layer 21 is not subjected to rubbing treatment. However, therubbing treatment may be applied thereto.

[0087] Meanwhile, the counter substrate 30 is constituted including aglass substrate 31, color filters 32 formed on one face side (lower sidein FIG. 8) of the glass substrate 31, and a common electrode 33. Thecolor filters 32 have three colors of red (R), green (G) and blue (B),and the color filter 32 of one of the colors is arranged in one pictureelement.

[0088] The common electrode 33 is formed under the color filters 32, andan alignment layer 34 made of polyimide or the like is formed under thecommon electrode 33. The surface of the alignment layer 34 is subjectedto rubbing treatment which decides orientation direction of liquidcrystal molecules when no electric field is applied thereto.

[0089] The TFT substrate 10 and counter substrate 30 are arrangedinterposing spacers (not shown) for maintaining a constant intervaltherebetween, and joined by a sealing material (not shown) coated ontothe outside of a display region.

[0090] In the liquid crystal display device of this embodiment,positions of the gate bus lines 12 a and the data bus lines 17 a aredifferent from those in a conventional transflective type liquid crystaldisplay device. Regions contributing neither to the reflectioncharacteristics nor the transmission characteristics in the conventionalliquid crystal display device, that is, the regions between the adjacentreflection electrodes are used as transmission regions in thisembodiment. The liquid crystal molecules in these regions are driven byan electric field transversely leaked from the reflection electrodes 20a.

[0091] Moreover, in this embodiment, the resist film 19 is divided foreach picture element. On the surface of this resist film 19,wrinkle-form ruggedness is provided by hardening and subjecting to heattreatment only a surface layer of the resist film 19, as will bedescribed later. It is confirmed, according to experiments by thepresent inventors, that a wrinkle-form rugged pattern formed on thesurface of the resist film is not uniform when the resist film is largein size, while a uniform wrinkle-form rugged pattern is formed inaccordance with the size of the resist film when the size of the resistfilm is made small. Accordingly, with considering conditions in actuallyusing the liquid crystal display device, the size of the resist film isset, to form a rugged pattern, so that light incident to a liquidcrystal panel from the upside can be reflected in the direction of anormal line of a panel surface. Thus, the utilization efficiency oflight is improved and visibility is improved.

[0092] Although it is not proven why the rugged pattern is uniformalizedwhen the size of the resist film is made small, the reason is estimatedas follows. That is, when the resist film is large in size, a portiongenerating ruggedness by heat treatment is not fixed. Moreover, theruggedness is independently generated at a plurality of portions.Therefore, the rugged pattern is not uniform. However, when the size ofthe resist film is small, the largest working portion of stress isperiodically generated in accordance with the size of the resist film.Therefore, the rugged pattern becomes uniform in accordance with thesize of the resist film. In order to obtain the above effects, it isnecessary to set one picture element electrode 20 a to a sizecorresponding to the resolution of 110 to 850 ppi.

[0093] Note that the rugged pattern formed on the resist film alsorelates to the film thickness of the resist film. In addition, in orderto efficiently reflect the light incident from the upside of the liquidcrystal display device in the direction of a normal line of a panelsurface, a flattened area (area where the average angle of inclinationis 5° or less) in a surface of the reflection electrode is preferablyset to 50% or more.

[0094] Hereafter, a manufacturing method for the liquid crystal displaydevice of this embodiment will be explained.

[0095]FIGS. 9A to 9M are schematic sectional views showing amanufacturing method for the TFT substrate of the liquid crystal displaydevice of this embodiment in a process order. First, as shown in FIG.9A, a metal film 12 is formed on the glass substrate 11 by sputtering,and a resist film 41 of a predetermined pattern is formed thereon usingphotoresist.

[0096] Next, as shown in FIG. 9B, the metal film 12 is etched using theresist film 41 as a mask to form the gate bus lines 12 a and storagecapacitor bus lines 12 b. Thereafter, the resist film 41 is removed.

[0097] Next, as shown in FIG. 9C, the gate insulating film 13 is formedon the entire upper surface of the glass substrate 11 by a plasma CVDmethod. Further, the amorphous silicon film 14 to be the operating layerof the TFT, and a SiN (silicon nitride) film 15 to be the channelprotection film are sequentially formed thereon.

[0098] Thereafter, a positive type photoresist film is formed on the SiNfilm 15. Then, the photoresist film is exposed to light from therearside of the glass substrate 11, and further exposed from thefrontside of the glass substrate 11 via a predetermined exposure mask.Thereafter, the photoresist film is subjected to a development processto form a resist film 42 covering channel protection film formingregions above the gate bus lines 12 a.

[0099] Next, as shown in FIG. 9D, the SiN film 15 is etched using theresist film 42 as a mask to form the channel protection films 15 a.Thereafter, the resist film 42 is removed.

[0100] Next, as shown in FIG. 9E, the n⁺ type amorphous silicon film 16to be the ohmic contact layer is formed on the entire upper surface ofthe glass substrate 11. Thereafter, a metal film 17 to be the data buslines, the source electrodes and the drain electrodes are formed by aPVD (Physical Vapor Deposition) method. Then, a resist film 45 of apredetermined pattern is formed on the metal film 17 using photoresist.

[0101] Next, as shown in FIG. 9F, the metal film 17, the n⁺ typeamorphous silicon film 16 and the silicon film 14 are etched to securethe shape of the silicon film 14 to be the operating layer of the TFT 7.Simultaneously, the data bus lines 17 a, the source electrodes 17 s, thedrain electrodes 17 d, and the storage capacitor electrodes 17 b areformed. At this time, part of the silicon film 14 intended to be achannel of the TFTs 7 is protected by the protection films 15 a.Thereafter, the resist film 45 is removed.

[0102] Next, as shown in FIG. 9G, the final protection film 18 is formedon the entire upper surface of the glass substrate 11 using, forexample, SiN. Then, a resist film 46 having contact hole forming partsopened thereon is formed on the final protection film 18.

[0103] Next, as shown in FIG. 9H, the final protection film 18 is etchedusing the resist film 46 as a mask to form contact holes 18 a and 18 breaching the source electrode 17 s and the storage capacitor electrode17 b, respectively. Thereafter, the resist film 46 is removed.

[0104] Next, as shown in FIG. 9I, the positive type photoresist film 19is formed on the entire upper surface of the glass substrate 11, whichis then subjected to exposure and development processes to form openingparts where the contact holes 18 a and 18 b are exposed and to dividethe resist film 19 for each picture element. Subsequently, post-bakingat a temperature of 130 to 145° C., the surface layer of the resist film19 is further irradiated with a UV ray (ultraviolet ray) to crosslinkthe polymers in the surface layer. Next when baking at a temperature of200° C. or more, since thermal deformation characteristics (coefficientof thermal expansion or of thermal shrinkage) between the surface layer(crosslinked part) and the deep part thereof (not crosslinked part) ofthe resist film 19 are different, fine wrinkle-form ruggedness isgenerated, as shown in FIG. 9J, on the surface of the resist film 19. Inthis case, as described before, the resist film 19 is divided into smallregions for each picture element in this embodiment, and therefore therugged pattern formed on the resist film 19 is uniformalized.

[0105] Note that in this embodiment, only the surface layer of theresist film 19 is hardened by UV irradiation. However, inner stresses inthe thickness direction of the resist film may be changed by irradiationof heat, plasma, UV, or ion beam.

[0106] Next, as shown in FIG. 9K, the entire upper surface of the glasssubstrate 11 is subjected to sputtering with Al to form a metal film 20.On the surface of the metal film 20 on the resist film 19, fineruggedness is formed following that of the resist film 19. This metalfilm 20 is electrically connected to the source electrodes 17 s and thestorage capacitor electrodes 17 b via contact holes 18 a and 18 b.Thereafter, a resist film 48 is formed in a predetermined pattern tosecure the shapes of the reflection electrodes.

[0107] Subsequently, as shown in FIG. 9L, the metal film 20 is etchedusing the resist film 48 as a mask to form a reflection electrode 20 afor each picture element. Thereafter, as shown in FIG. 9M, the resistfilm 48 is removed. Then, an alignment layer (not shown) made ofpolyimide and the like is formed on the entire upper surface of theglass substrate 11. In this way, the reflection electrodes 20 a havingfinely rugged surfaces is formed.

[0108] Hereafter, a manufacturing method of the counter substrate 30will be explained. First, a red color-photosensitive resin, a greencolor-photosensitive resin, and a blue color-photosensitive resin areused to form the color filters 32 on one face (on the lower face in FIG.8) of the glass substrate 31.

[0109] Next, ITO is sputtered onto the color filters 32 to form thetransparent common electrode 33. Then, the alignment layer 34 made ofpolyimide is formed on the common electrode 33, thereby completing thecounter substrate 30.

[0110] Next, the spacers (not shown) are arranged for maintaining aconstant interval between the TFT substrate 10 and the counter substrate30, and the liquid crystal 40 is enclosed between the TFT substrate 10and the counter substrate 30 using a vacuum injection method or adropping injection method. In this way, the transflective type liquidcrystal display device as shown in FIGS. 7 and 8 is completed.

[0111]FIG. 10 is a view showing relations of transmissive aperture ratioand effective reflection area ratio to resolution, between theconventional transflective type liquid crystal display device shown inFIG. 1 and the transflective type liquid crystal display device of thisembodiment, with the resolution (ppi) as the abscissa and withtransmissive aperture ratio (left axis) and effective reflection arearatio (right axis) as the ordinate. Herein, in the conventional liquidcrystal display device, the transmissive aperture ratio is fixed to be14% regardless of the resolution. In addition, an inter-picture elementinterval is set to 8 μm, a width of the data bus lines is set to 5 μm, awidth of the storage capacitor bus lines is set to 12 μm, and a width ofthe gate bus lines is set to 10 μm.

[0112] As shown in this FIG. 10, in the conventional liquid crystaldisplay device, the effective reflection area ratio is about 74% whenthe resolution is 125 ppi, and as the resolution is higher, theeffective reflection area ratio is decreased. Meanwhile, in the liquidcrystal display device of this embodiment, the transmissive apertureratio is about 14% and the effective reflection area ratio is about 85%when the resolution is 125 ppi, and thereby it is clarified that theeffective reflection area ratio is large compared with the conventionalexample. Moreover, in this embodiment, when the resolution is about 180ppi, the transmissive aperture ratio is about 18%, and the effectivereflection area ratio is about 78%. In order to recognize smallcharacters described in catalogues or the like, the resolution of 180ppi or more is required. That is, from FIG. 10, it is found that theliquid crystal display device of this embodiment is good in reflectioncharacteristics and transmission characteristics, and excellent invisibility, even though having high resolution of about 180 ppi.

[0113]FIG. 11 shows microscopic images obtained by checking a reflectionstate and a transmission state at displaying when applied voltages are 0V and 2.3 V, in the liquid crystal display device manufactured accordingto this embodiment. Herein, the resolution of this liquid crystaldisplay device corresponds to 180 ppi, and a cell gap is 3 m, and ann-type nematic liquid crystal is enclosed between the TFT substrate andthe counter substrate after the vertical alignment of these substratesis subjected to rubbing treatment. A design values of a photomask usedfor manufacturing the liquid crystal display device is also shown inFIG. 11. Moreover, FIG. 12 shows an AFM (Atomic Force Microscope) imageof the reflection electrodes of the liquid crystal display device. It isfound from FIG. 11 that good characteristics can be obtained in any caseof using the liquid crystal display device as a reflection type liquidcrystal display device and as a transmission type liquid crystal displaydevice.

Second Embodiment

[0114]FIG. 13A is a plan view showing a transflective type liquidcrystal display device of a second embodiment of the present invention.This embodiment is different from the first embodiment in that thereflection electrode is provided with slits. The other structure isbasically the same as that of the first embodiment, and thereforeoverlapping explanation will be omitted.

[0115] In this embodiment, as shown in FIG. 13A, a plurality of slits 52are provided on a reflection electrode 51 and a resist film disposedthereunder, in parallel to the gate bus line 12 a. That is, by theseslits 52, the resist film is divided into a plurality of regions in onepicture element.

[0116] As described before, a rugged pattern formed on the resist filmis determined depending on the size of the resist film. Like thisembodiment, by providing the slits 52 on the reflection electrode 51 andthe resist film thereunder, a desired rugged pattern can be formed onthe reflection electrode 51 even when the reflection electrode 51 islarge in size. In addition, slit 52 portions serve as transmissionregions, thereby heightening the transmissive aperture ratio. Slits 53or 54 having the shapes as shown in FIGS. 13B and 13C, respectively, mayalso be formed according to a desired rugged pattern. In order to surelyform ruggedness of a uniform pattern, any short side of the regionsdivided by the slits 52, 53 and 54 is preferably 5 μm.

[0117]FIG. 14 is a view showing relations of transmissive aperture ratioand effective reflection area ratio to resolution, between theconventional transflective type liquid crystal display device shown inFIG. 1 and the transflective type liquid crystal display device of thisembodiment, with the resolution (ppi) as the abscissa and withtransmissive aperture ratio (left axis) and effective reflection arearatio (right axis) as the ordinate. Herein, in the conventional liquidcrystal display device, the transmissive aperture ratio is fixed to be14% regardless of the resolution. In addition, an inter-pixel intervalis set to 8 μm, a width of the data bus lines is set to 5 μm, a width ofthe storage capacitor bus lines is set to 12 μm, and a width of the gatebus lines is set to 10 μm.

[0118] As clarified from the FIG. 14, in this embodiment, ruggedness canbe formed in a desired pattern even in the reflection type liquidcrystal display device with a resolution of 125 ppi or less, andtherefore the transflective type liquid crystal display device havinghigh utilization efficiency of light is achieved.

[0119]FIG. 15 shows microscopic images obtained by checking a displaystate at displaying when applied voltages are 0V and 2.3 V, in theliquid crystal display device manufactured according to this embodiment.Designed values of a photomask used for manufacturing the liquid crystaldisplay device is also shown in FIG. 15. It is found from the FIG. 15that uniform rugged patterns are formed for each picture element.

Third Embodiment

[0120]FIG. 16A is a plan view showing a transflective type liquidcrystal display device of a third embodiment of the present invention.Note that this embodiment is different from the first embodiment in thatthe reflection electrode is not provided with a rugged surface, and thereflection electrode is provided with slits. The other structure isbasically the same as that of the first embodiment, and thereforeoverlapping explanation will be omitted.

[0121] In this embodiment, as shown in FIG. 16A, a reflection electrode61 is provided with slits 62, and slit 62 portions serve as transmissionregions. Slits 63 and 64 in the shapes as shown in FIGS. 16B and 16C,respectively, may also be provided. However, the shapes of the slits arepreferably common to each picture element. Moreover, any short side ofthe regions divided by the slits is preferably 5 μm or more.

[0122] In this embodiment, the reflection electrode 61 is formed so asto overlap the gate bus line 12 a, the data bus line 17 a, and the TFT7. Moreover, the region between the adjacent reflection electrodes 61serves as a light transmission region. Further, the reflection electrode61 is provided with the slits 62 so as to serve as a light transmissionregion. Accordingly, in the liquid crystal display device of thisembodiment, the transmissive aperture ratio is high compared with theconventional one, thereby improving the reflection characteristics aswell as the transmission characteristics.

[0123]FIG. 17 shows microscopic images obtained by checking a displaystate at displaying when applied voltages are 0V and 2.3 V, in theliquid crystal display device manufactured according to this embodiment.Design values of a photomask used in manufacturing the liquid crystal isalso shown in FIG. 17. From the FIG. 17, according to this embodiment,it is found that the reflection type liquid crystal display devicehaving high utilization efficiency of light and good visibility evenwhen the resolution is 125 ppi or less, can be achieved.

[0124] Note that in any of the above first to third embodiments,explanation was given to the case of applying the present invention tothe vertically aligned (VA) type liquid crystal display device. However,the application of the present invention is not thereby limited to thevertically aligned type liquid crystal display device. The presentinvention can also be applied to a horizontally aligned type liquidcrystal display device, a hybrid alignment type liquid crystal displaydevice and the like.

Fourth Embodiment

[0125] A liquid crystal display device according to a fourth embodimentof the present invention will be explained with reference to FIGS. 18 to28. First, a first basic structure of the present invention, which is apresupposition of this embodiment, will be explained by use of FIGS. 18to 28. FIG. 18 shows an outline structure of a liquid crystal displaydevice according to this basic structure. As shown in FIG. 18, forexample, the VA (Vertically Aligned) type liquid crystal display devicehas a structure in which a TFT substrate 202 and a counter substrate 204are opposingly aligned with each other, and a liquid crystal 206 (notshown in FIG. 18) is enclosed therebetween. The TFT substrate 202 has apicture element electrode, a TFT and the like formed thereon for eachpicture element region, and the counter substrate 204 has a CF (colorfilter) layer and the like formed thereon. The liquid crystal 206 has anegative dielectric anisotropy. On the opposing surfaces of the bothsubstrates 202 and 204, a vertically aligned film is formed for aligningliquid crystal molecules, for example, in the vertical direction to thesurfaces of the substrates.

[0126] On the TFT substrate 202, a gate bus line drive circuit 280 and adata bus line drive circuit 282 are provided. The gate bus line drivecircuit 280 has a driver IC mounted thereon for driving a plurality ofgate bus lines, and the data bus line drive circuit 282 has a driver ICmounted thereon for driving a plurality of data bus lines. Both of thedrive circuits 280 and 282 are adapted to output scanning signals anddisplay signals to the predetermined gate bus lines or data bus linesbased on predetermined signals outputted from a control circuit 284.

[0127] On the surface opposite to the element forming surface of the TFTsubstrate 202, a polarizing plate 287 is stuck. On the other surface ofthe polarizing plate 287 on the opposite side to the TFT substrate 202,for example, a backlight unit 288 including a linear primary lightsource and a surface light guide plate, is disposed. Meanwhile, on theother surface of the counter substrate 204 on the opposite side to theresin CF layer forming surface, a polarizing plate 286 is stuck. Alinearly polarizing plate or the combination of a linearly polarizingplate and a ¼-wavelength plate is used for the light polarizing plates286 and 287.

[0128]FIG. 19 shows a schematic sectional structure of three pictureelements of the liquid crystal display device according to this basicstructure. As shown in FIG. 19, data bus lines 214, extending in thevertical direction to the paper surface, are formed on a glass substrate210 of the TFT substrate 202. A flattening film 232 is formed on thedata bus lines 214. Note that an insulating film formed on the lowerlayer of the data bus line 214 is not shown. Reflection electrodes 216are formed on the flattening film 232. Ruggedness is formed on thesurfaces of the reflection electrodes 216 so as to improve lightreflection characteristics. The regions where the reflection electrodes216 are formed to serve as reflection regions R1. In the reflectionelectrodes 216, opening parts are formed. The regions where the openingparts are formed serve as transmission regions T1. The reflection regionR1 and the transmission region T1 constitute a picture element region P.Note that the surface of the reflection electrode 216 is formed into amirror plane, and a forward scattering film may be arranged on thedisplay screen side.

[0129] On a glass substrate 211 of the counter substrate 204, CF layersR, G and B, obtained by mixing a pigment or a dye with a transparentresin, are formed. Each layer of the CF layers R, G, and B is formed bya multilayered dielectric film, and functions as a wavelength selectinglayer for selecting and transmitting the light of R, G or B,respectively. The CF layers R, G, and B are formed in the transmissionregions T1 of the picture elements P, extending up to a part of thereflection regions R1. The CF layers R, G, and B have the same colorpurity in the part of the reflection regions R1 and in the transmissionregions T1.

[0130] In this basic structure, the CF layers are formed in the part ofthe reflection regions R1, and in a reflection mode display, the lighttransmitting the CF layers twice and the light not transmitting the CFlayers are mixed. Therefore, a display with high luminance can beobtained, and if the area ratio of the region of the reflection regionsR1 where the CF layers are formed to the entire reflection regions R1 isadjusted, color purity at the time of displaying in the reflection modecan be close to the color purity at the time of displaying in thetransmission mode. Accordingly, the transflective type liquid crystaldisplay device having good display quality can be achieved.

[0131] Moreover, in this basic structure, even though alignmentdeviation occurs between the TFT substrate 202 and the counter substrate204, if the area ratio of the region of the reflection regions R1 wherethe CF layers are formed to the entire reflection regions R1 is notchanged, display characteristics at the time of displaying in thereflection mode are not changed. Moreover, if the area ratio of theregion of the transmission regions T1 where the CF layers are formed tothe entire transmission regions T1 (100% in this basic structure) is notchanged, display characteristics at the time of displaying in thetransmission mode is not changed. The CF layers are formed substantiallyaround the transmission regions T1 in a width larger than the width ofthe transmission regions T1, to prevent the above-described area ratiofrom changing even when the alignment deviation occurs. Therefore,sufficient alignment margins can be secured, thereby preventing thedegradation in the display quality due to the alignment deviation.

[0132] Next, a liquid crystal display device according to a second basicstructure of the present invention will be explained by use of FIG. 20.FIG. 20 shows a schematic sectional structure of three picture elementsof the liquid crystal display device according to this basic structure.As shown in FIG. 20, the counter substrate 204 has CF layers C (cyan), M(magenta), and Y (yellow), which are complementary colors of R, G and B,for transmitting the light of the wavelengths of C, M and Y. Each colorof R, G and B is displayed by the combinations of each color of C, M andY.

[0133] The reflection electrodes 216 are formed so as to cover the databus lines 214. The regions where the reflection electrodes 216 areformed serve as reflection regions R1. In the reflection electrodes 216,opening parts are formed. The regions where the opening parts are formedserve as transmission regions T1. Moreover, in this structure, theregion from an edge of each reflection electrode 216 to substantiallythe central part of a gap region between the adjacent reflectionelectrodes 216, is used as a transmission region T2. The reflectionregion R1 and the transmission regions T1 and T2 constitute a pictureelement region P. The liquid crystal 206 in the transmission regions T1and T2 is driven similarly to the liquid crystal 206 in the reflectionregions R1 in the same picture element regions P, by an oblique electricfield between the reflection electrodes 216 and a common electrode (notshown).

[0134] Each layer of the CF layers C, M, and Y is formed in thetransmission region T1, extending up to part of the reflection regionR1. Moreover, in the transmission regions T1 on the CF layers C, M andY, the CF layers of different colors are laminated, extending up to bothsides of the reflection regions R1. That is, layered parts where any twolayers of the CF layers C, M, Y are laminated are formed in part of thereflection regions R1 and the transmission regions T1 of the pictureelement regions P. In the remaining regions of the reflection regions,single layer parts of only one layer of the CF layers C, M and Y, areformed. In the transmission region T1 of a picture element displaying R(RED), two layers of the CF layers M and Y are sequentially laminated.In the transmission region T1 of a picture element displaying G (GREEN),two layers of the CF layers Y and C are sequentially laminated. In thetransmission region T1 of a picture element displaying B (BLUE), twolayers of the CF layers C and M are sequentially laminated. Note thatthe order of laminating the CF layers is not limited to the orders asdescribed above.

[0135] Moreover, in the reflection regions R1 of a picture elementdisplaying R, the CF layers M and Y are formed with almost the sameareas. In the reflection regions R1 of a picture element displaying G,the CF layers Y and C are formed with almost the same areas. In thereflection regions R1 of a picture element displaying B, the CF layers Cand M are formed with almost the same areas.

[0136] In this basic structure, single layers of the CF layers C, M andY are formed in part of the reflection regions R1. For example, in apicture element displaying G, when displaying in the reflection mode,the light transmitted through a single layer part including the CF layerC, and the light transmitted through a single layer part including theCF layer Y, are mixed. The CF layer C absorbs the wavelength of R, andtherefore the light transmitted through the CF layer C has thewavelengths of B and G. Moreover, the CF layer Y absorbs the wavelengthof B, and therefore the light transmitted through the CF layer Y has thewavelengths of R and G. For this reason, the mixed light has a peak atthe wavelength of G to be viewed by an observer of the display screen asa light of almost green. Meanwhile, when displaying in the transmissionmode, the light transmitted through the layered part where the CF layersC and Y are laminated, has the wavelength of G.

[0137] Herein, the mixed light when displaying G in the reflection modealso has the wavelengths of R and B. Therefore, chromaticity deviationoccurs between a reflection mode display of G and a transmission modedisplay of G. Therefore, layered parts with the same structure as thatof the transmission regions T1 are arranged in part of the reflectionregions R1. The area ratio of the region of the reflection regions R1where the layered parts are arranged to the entire reflection regions R1is adjusted, thereby making the color purity of the reflection modedisplay closer to the color purity of the transmission mode display.Thus, the transflective type liquid crystal display device with gooddisplay quality can be obtained.

[0138] Further, in this structure similarly to the first basicstructure, even though alignment deviation occurs between the TFTsubstrate 202 and the counter substrate 204, if the area ratio of theregion of the reflection regions R1 where the layered parts are arrangedto the entire reflection regions R1 does not change, displaycharacteristics in the reflection mode are not changed. Moreover, if thearea ratio of the region of the transmission regions T1 where thelayered parts are arranged to the entire transmission regions T1 (100%in this basic structure) does not change, display characteristics in thetransmission mode are not changed. The layered parts are formedsubstantially around the transmission regions T1, in a width larger thanthe width of the transmission region T1, to prevent the above-describedarea ratio from changing even when alignment deviation occurs.Therefore, sufficient alignment margins can be secured, therebypreventing the degradation in the display quality due to the alignmentdeviation.

[0139] Next, a liquid crystal display device according to a third basicstructure of the present invention will be explained with reference toFIGS. 21A and 21B. FIG. 21A shows a schematic sectional structure of theliquid crystal display device according to this basic structure. Asshown in FIG. 21A, the CF layers R, G and B of the counter substrate 204are formed in part of the reflection regions R1 and in the transmissionregions T1 of the picture element regions. On the entire surface of thesubstrate on the CF layers R, G, and B, a flattening film 233 forflattening the ruggedness on the surface of the counter substrate 204,is formed. With this structure, turbulence of orientation of the liquidcrystal 206 caused by the ruggedness on the surface of the substrate canbe suppressed, thereby improving orientation stability of the liquidcrystal 206.

[0140]FIG. 21B shows another example of the schematic sectionalstructure of the liquid crystal display device according to this basicstructure. As shown in FIG. 21B, on the counter substrate 204, layeredparts including the laminates of the CF layers C, M and Y are formed ina part of the reflection regions R1 and in the transmission regions T1.Single layer parts of the CF layers C, M, and Y are formed in thetransmission regions T1. On the entire surface of the substrate on theCF layers C, M and Y, the flattening film 233 for flattening theruggedness on the surface of the counter substrate 204 is formed. Withthis structure, turbulence of the orientation of the liquid crystal 206caused by the ruggedness on the surface of the substrate can besuppressed, thereby improving orientation stability of the liquidcrystal 206.

[0141] Next, a liquid crystal display device according to a fourth basicstructure of the present invention will be explained by use of FIGS. 22Aand 22B. FIG. 22A shows a schematic sectional structure of the liquidcrystal display device according to this basic structure. As shown inFIG. 22A, on the CF layers R, G, and B of the counter substrate 204, andin the regions other than the transmission regions T1, the flatteningfilm 233 is formed. A cell thickness dt in the transmission regions T1where no flattening film 233 is formed is about 1 to 2.3 times(preferably about 1.7 to 2.3 times) a cell thickness dr in thereflection regions R1 where the flattening film 233 is formed. Whendisplaying in the transmission mode, the light incident from a backlightunit side passes the liquid crystal 206 only once to emit toward adisplay screen side. On the other hand, when displaying in thereflection mode, the light incident from the display screen side passesthe liquid crystal 206, is reflected by the reflection electrodes 216,and passes the liquid crystal 206 again to be emit toward the displayscreen side. Specifically, in this basic structure, the cell thicknessdt in the transmission regions T1 is made almost twice the cellthickness dr in the reflection regions R1. Accordingly, a substantialretardation (Δn·d) generated in the liquid crystal 206 in thetransmission mode display is made nearly the same as that generated inthe reflection mode display. Therefore, according to this basicstructure, almost the same display characteristics between both themodes of transmission and reflection can be obtained. Note that in thisbasic structure, by forming the flattening film 233 on the CF substrate204 in the region other than the transmission regions T1, the cellthickness dt in the transmission regions T1 and the cell thickness dr inthe reflection regions R1 are made different. However, using theflattening film 232 on the TFT substrate 202, the cell thicknesses dtand dr may be made different.

[0142]FIG. 22B shows another example of the schematic sectionalstructure of the liquid crystal display device according to this basicstructure. As shown in FIG. 22B, on the CF layers C, M and Y of thecounter substrate 204 and in the region other than the transmissionregions T1, the flattening film 233 is formed. The cell thickness dt inthe transmission regions T1 where no flattening film 233 is formed isabout 1 to 2.3 times (preferably about 1.7 to 2.3 times) the cellthickness dr in the reflection regions R1 where the flattening film 233is formed. According to this example also, almost the same displaycharacteristics can be obtained in both the modes of transmission andreflection.

[0143]FIG. 23 shows further another example of the schematic sectionalstructure of the liquid crystal display device according to this basicstructure. As shown in FIG. 23, on the CF layers C, M and Y of thecounter substrate 204 and in the region other than the transmissionregions T1 and T2, the flattening film 233 is formed. A cell thicknessdt1 in the transmission regions T1 where no flattening film 233 isformed and a cell thickness dt2 in the transmission regions T2 are about1 to 2.3 times (preferably about 1.7 to 2.3 times) the cell thickness drin the reflection regions R1 where the flattening film 233 is formed.According to this example also, almost the same display characteristicscan be obtained in both the modes of transmission and reflection.

[0144] Next, a liquid crystal display device according to example 1 ofthis embodiment will be explained by use of FIGS. 24A and 24B. FIG. 24Ashows a structure of the liquid crystal display device according toexample 1, and FIG. 24B shows an outline sectional structure of theliquid crystal display device taken along the line IV-IV of FIG. 24A. Asshown in FIGS. 24A and 24B, on the TFT substrate 202 of the liquidcrystal display device, a plurality of gate bus lines 212 extending inright and left directions of FIG. 24A in parallel with each other, areformed. In addition, on the TFT substrate 202, a plurality of data buslines 214, intersecting the gate bus lines 212 via an insulating film(not shown), and extending in the vertical direction of FIG. 24A inparallel with each other, are formed. In the vicinity of eachintersection position of the gate bus line 212 and the data bus line214, a TFT 220 is formed. The TFT 220 has a working semiconductor film(not shown) made of a-Si (amorphous silicon) for example. On the workingsemiconductor film, a channel protection film (not shown) is formed. Onthe channel protection film, a drain electrode 221 led out from theadjacent data bus line 214, and a source electrode 222 are formed so asto face each other interposing a predetermined gap therebetween. In thisstructure, the gate bus lines 212 directly under the channel protectionfilm is adapted to function as a gate electrode of the TFT 220.

[0145] In the regions surrounded by the gate bus lines 212 and the databus lines 214, the reflection electrodes 216 made of Al etc., areformed. The regions where the reflection electrodes 216 are formed serveas reflection regions. The reflection electrodes 216 are electricallyconnected to the source electrodes 222 via contact holes 224. Parts ofthe reflection electrodes 216 are opened and transparent electrodes 217made of ITO etc., are formed therein. The regions where the transparentelectrodes 217 are formed serve as transmission regions. The reflectionregions and the transmission regions constitute picture element regions.The reflection electrode 216 and the transparent electrode 217 in onepicture element are electrically connected via a barrier metal layer250.

[0146] Further, on the TFT substrate 202, storage capacitor bus lines218, crossing the picture element regions, are formed in parallel to thegate bus lines 212. On the storage capacitor bus lines 218, a storagecapacitor electrode 219 is formed for each picture element region. Thestorage capacitor electrodes 219 are electrically connected to thereflection electrodes 216 via contact holes 226.

[0147] On the glass substrate 211 of the CF substrate (countersubstrate) 204, any of the CF layers R, G and B for an LCD monitor isformed in part of the reflection regions and in the transmissionregions. The CF layers R, G and B are formed with such a film thicknessthat good color purity can be obtained in the transmission mode display.A flattening film 233 is formed on the entire surface of the substrateon the CF layers R, G and B. A common electrode 252 is formed on theentire surface of the substrate on the flattening film 233.

[0148]FIG. 25 is an x-y chromaticity chart of the liquid crystal displaydevice of this example 1. A solid line a in the chart shows a colorreproducing range (an ideal value) in the reflection mode of the liquidcrystal display device in which the area ratio of the region of thereflection regions where the CF layers are formed to the entirereflection regions is 90%. Similarly, a solid line b shows a colorreproducing range of the liquid crystal display device having theabove-described area ratio of 80% in the reflection mode, a solid line cshows a color reproducing range of the liquid crystal display devicehaving the area ratio of 70% in the reflection mode, and a solid line dshows a color reproducing range of the liquid crystal display devicehaving the above-described area ratio of 50% in the reflection mode. Abroken line e shows a color reproducing range (an ideal value) of aconventional reflection type liquid crystal display device in which CFlayers having the film thickness of 0.75 m are used. As shown in FIG.25, according to example 1, by setting the above-described area ratio to70% to 90%, a reflection mode display, in which the color reproducingrange is wider than that of the conventional reflection type liquidcrystal display device, can be obtained. In addition, since the CFlayers for an LCD monitor are used in example 1, the same colorreproducing range as that of the LCD monitor can be obtained in thetransmission mode.

[0149] In example 1, similarly to the first basic structure, the CFlayers are formed in part of the reflection regions, and in a reflectionmode display, the light transmitted through the CF layers twice and thelight not transmitted through the CF layers are mixed. Therefore, adisplay with high luminance can be obtained. Moreover, the area ratio ofthe region of the reflection regions where the CF layers are formed tothe entire reflection regions is adjusted, thereby making the colorpurity in the reflection mode display closer to the color purity in thetransmission mode display. Thus, the transflective type liquid crystaldisplay device with good display quality can be obtained.

[0150] Moreover, in example 1, similarly to the first basic structure,even though alignment deviation occurs between the TFT substrate 202 andthe counter substrate 204, if the area ratio of the region of thereflection regions where the CF layers are formed to the entirereflection regions is not changed, display characteristics in thereflection mode are not changed. Moreover, if the area ratio of theregion of the transmission regions where the CF layers are formed to theentire transmission regions (100% in example 1) is not changed, displaycharacteristics in the transmission mode are not changed. The CF layersare formed in a width wider than that of the transmission regions toprevent the above-described area ratio from changing even when thealignment deviation is generated. Therefore, sufficient alignmentmargins can be secured, thereby preventing the degradation in thedisplay quality due to the alignment deviation.

[0151] Further, in example 1, the reflection electrodes 216 are formedso as to cover the TFTs 220 for driving the adjacent picture elementslocated on the lower side in FIG. 24A and the gate bus lines 212.Therefore, when a predetermined potential is written in the reflectionelectrodes 216, voltage is not applied to the gate bus line 212 on thelower side of the reflection electrodes 216. Instead, the voltage isapplied to the adjacent gate bus line 212 on the upper side of thereflection electrodes 216. Accordingly, a picture element potential isnot affected by an electric field of the gate bus lines 212, andtherefore the occurrence of a flicker and a luminance inclination can beprevented.

[0152] In example 1, the reflection electrodes 216 are formed so as tocover the TFTs 220 for driving the adjacent picture elements on thelower side, and the gate bus lines 212. However, the reflectionelectrodes 216 may be formed in the regions surrounded by the gate buslines 212 and the data bus lines 214. By applying example 1 to thestructure of the conventional liquid crystal display device shown inFIG. 1, the liquid crystal display device with good display quality canbe obtained.

[0153] Next, a liquid crystal display device according to example 2 ofthis embodiment will be explained by use of FIGS. 26A and 26B. FIG. 26Ashows a structure of the liquid crystal display device according to thisexample, and FIG. 26B shows an outline sectional structure of the liquidcrystal display device taken along the line V-V of FIG. 26A. As shown inFIGS. 26A and 26B, the reflection electrodes 216 are formed so as tocover the data bus lines 214, the TFTs 220 for driving the adjacentpicture elements located on the lower side in FIG. 26A, and the gate buslines 212. The regions where the reflection electrodes 216 are formedserve as reflection regions. The regions between the adjacent reflectionelectrodes 216 are used as transmission regions. The liquid crystal 206in the transmission regions is driven similarly to the liquid crystal206 in the reflection regions, by an oblique electric field between thereflection electrodes 216 and a common electrode (not shown). In part ofthe reflection regions and in the transmission regions on the countersubstrate 204, any one of the CF layers R, G and B is formed for eachpicture element. In the example 2 also, the effects similar to those inexample 1 can be obtained. In addition, by applying example 2 to thestructure of the conventional liquid crystal display device shown inFIGS. 2 and 3, the liquid crystal display device with good displayquality can be obtained.

[0154] Next, a liquid crystal display device according to example 3 ofthis embodiment will be explained by use of FIGS. 27A and 27B. FIG. 27Ashows a structure of the liquid crystal display device according toexample 3, and FIG. 27B shows an outline sectional structure of theliquid crystal display device taken along the line VI-VI of FIG. 27A. Asshown in FIGS. 27A and 27B, in the reflection electrodes 216, openingparts 260 a to 260 c opened in various shapes are formed. For example,in the reflection electrode 216 for the left picture element of threepicture elements shown in FIG. 27A, a plurality of diamond-shapedopening parts 260 a are formed. Moreover, a plurality of rectangularopening parts 260 b having long sides almost in parallel to theextending direction of the gate bus lines 212, are formed in thereflection electrode 216 for the middle picture element of the threepicture elements. In the reflection electrode 216 for the right pictureelement, a plurality of rectangular opening parts 260 c having longsides almost in parallel to the extending direction of the data buslines 214, are formed. The regions where the reflection electrodes 216are formed serve as reflection regions, and the regions where theopening parts 260 a to 260 c are formed serve as transmission regions.The liquid crystal 206 in the transmission regions is driven similarlyto the liquid crystal 206 in the reflection regions, by an obliqueelectric field between the reflection electrodes 216 and a commonelectrode (not shown).

[0155] In part of the reflection regions and in the transmission regionson the counter substrate 204, any one of the CF layers R, G and B isformed for each picture element. The reflection electrodes 216 areformed so as to cover the TFTs 220 for driving the adjacent pictureelements located on the lower side in FIG. 27A and the gate bus lines212. According to example 3, the effects similar to those in example 1and example 2 can be obtained.

[0156] In example 3, the reflection electrodes 216 are formed so as tocover the TFTs 220 for driving the adjacent picture elements located onthe lower side and the gate bus lines 212. However, the reflectionelectrodes 216 may be formed in the regions surrounded by the gate buslines 212 and the data bus lines 214. By applying example 3 to thestructure of the conventional liquid crystal display device shown inFIG. 4, the liquid crystal display device with good display quality canbe obtained.

[0157] Next, a liquid crystal display device according to example 4 ofthis embodiment will be explained by use of FIGS. 28A and 28B. FIG. 28Ashows a structure of the liquid crystal display device according toexample 4, and FIG. 28B shows an outline sectional structure of theliquid crystal display device taken along the line VII-VII of FIG. 28A.As shown in FIGS. 28A and 28B, the reflection electrodes 216 are formedso as to cover the gate bus lines 212, the data bus lines 214, and theTFTs 220. In the reflection electrodes 216, a plurality of opening parts260 opened in a nearly elliptical shape are formed. The regions wherethe opening parts 260 are formed serve as transmission regions T1. Theregions where the reflection electrodes 216 are formed serve asreflection regions. Moreover, the regions where the opening parts 260are formed and the regions between the adjacent reflection electrodes216 serve as transmission regions. The liquid crystal 206 in thetransmission regions is driven similarly to the liquid crystal 206 inthe reflection regions, by an oblique electric field between thereflection electrodes 216 and a common electrode (not shown).

[0158] The counter substrate 204 have the CF layers C, M and Y fortransmitting the light having the wavelengths of C, M and Y which arecomplementary colors of R, G and B. The CF layers C, M, and Y constitutelayered parts where two layers are laminated, in part of the reflectionregions and in the transmission regions. Moreover, the CF layers C, M,and Y constitute single layer parts having only one layer in the otherregions. In the transmission region of a picture element displaying R,two layers of the CF layers M and Y are laminated. In the transmissionregion of a picture element displaying G, two layers of the CF layers Yand C are laminated. In the transmission region of a picture elementdisplaying B, two layers of the CF layers C and M are laminated. On theCF layers C, M, and Y, the flattening film 233 is formed. According tothe example 4, the effects similar to those in example 1 to example 3can be obtained. In addition, since the flattening film 233 is formed onthe CF layers C, M, and Y, orientation stability of the liquid crystal206 can be improved similarly to the third basic structure. Moreover, byapplying example 4 to the structure of the conventional liquid crystaldisplay device shown in FIG. 5, the liquid crystal display device withgood display quality can be obtained.

[0159] As described above, according to this embodiment, the liquidcrystal display device having high utilization efficiency of light andgood display quality can be achieved at low cost.

Fifth Embodiment

[0160] Next, a liquid crystal display device according to the fifthembodiment of the present invention will be explained by use of FIGS. 29and 30. FIG. 29 shows a structure of the liquid crystal display deviceaccording to this embodiment. Note that constituent componentsfunctioning similarly to those of the liquid crystal display deviceaccording to the fourth embodiment are designated by the same numeralsand symbols, and explanation thereof is omitted. As shown in FIG. 29,the reflection electrodes 216 a to 216 e constituting the reflectionregions of the transflective type liquid crystal display device areformed in the regions partitioned by the gate bus lines 212 and the databus lines 214. In the reflection electrodes 216 a, 216 b, 216 d, and 216e, opening parts 260 a, 260 b, 260 d, and 260 e, opened in variousshapes such as a slit-like shape and a circular hole-like shape, arerespectively formed. Further, in the peripheral parts of the reflectionelectrodes 216 a to 216 e, notched parts 260 a′ to 260 e′, cut intovarious shapes such as a slit-like shape and a circular or polygonalhole-like shape, are respectively formed.

[0161] For example, in the reflection electrode 216 a, one slit-shapedopening part 260 a extending almost in parallel to the long sides of thereflection electrode 216 a, and slit-shaped notched parts 260 a′ cutinside from the two opposing long sides of the reflection electrode 216a and extending obliquely to both the long sides, are formed. In thereflection electrode 216 b, a plurality of slit-shaped opening parts 260b extending almost in parallel to the short sides of the reflectionelectrode 216 b, and a plurality of slit-shaped notched parts 260 b′ cutinside from both the long sides of the reflection electrode 216 b andextending almost in parallel to the short sides of the reflectionelectrode 216 b, are formed. In the reflection electrode 216 c, aplurality of wedge-like notched parts 260 c′ cut from both the longsides of the reflection electrode 216 c and extending almost in parallelto the short sides of the reflection electrode 216 c, are mutuallyadjacently formed. In the reflection electrode 216 d, a plurality ofcircular opening parts 260 d, and a plurality of circular notched parts260 d′ cut from both the short sides and both the long sides of thereflection electrode 216 d, are formed. In the reflection electrode 216e, one slit-shaped opening part 260 e extending almost in parallel tothe long sides of the reflection electrode 216 e, and a plurality ofwedge-like notched parts 260 e′ cut from both the long sides of thereflection electrode 216 e and extending almost in parallel to the shortsides of the reflection electrode 216 e, are formed.

[0162] The regions where the reflection electrodes 216 a to 216 e areformed serve as reflection regions. The regions where the opening parts260 a, 260 b, 260 d, and 260 e are formed, and the regions where thenotched parts 260 a′ to 260 e′ of the peripheral parts of the reflectionelectrodes 216 a to 216 e serve as transmission regions. No transparentelectrodes are formed in the opening parts 260 a, 260 b, 260 d, and 260e, and in the notched parts 260 a′ to 260 e′. Liquid crystal moleculesin the transmission regions are driven almost similarly to the liquidcrystal molecules in the reflection regions of the same picture element,by an oblique electric field between end portions of the reflectionelectrodes 216 a to 216 e and a common electrode 252 (not shown in FIG.29) on a counter substrates 204 side.

[0163] In FIG. 29, the opening parts 260 a, 260 b, 260 d, and 260 e andthe notched parts 260 a′ to 260 e′ are formed in different shapes foreach picture element. However, all of the opening parts 260 a, 260 b,260 d, and 260 e and the notched parts 260 a′ to 260 e′ may be formed inthe same shapes for each picture element. In addition, each opening part260 a, 260 b, 260 d, and 260 e and each notched part 260 a′ to 260 e′may have a shape to restrict the alignment of the liquid crystalmolecules. With this structure, in the liquid crystal display device ofVA mode in which the liquid crystal molecules are aligned almostperpendicular to the substrates, alignment division dispensing withrubbing treatment of an alignment layer is enabled. Note that althoughrubbing treatment is required, this embodiment is applicable to theliquid crystal display devices of TN mode in which a horizontallyaligned layer is used, and of HAN (Hybrid Aligned Nematic) mode in whichhorizontally aligned layer and vertically aligned layer are used.According to this embodiment, good transmission characteristics can beobtained compared with the conventional transflective type liquidcrystal display device shown in FIG. 4.

[0164]FIG. 30 shows a modified example of the structure of the liquidcrystal display device according to this embodiment. As shown in FIG.30, reflection electrodes 216 f to 216 k are formed at intersectionpositions of both bus lines 212 and 214 and on the upper layer of theTFTs 220. Moreover, in the reflection electrodes 216 f to 216 k,various-shaped opening parts 260 i and notched parts 260 f′ to 260 k′are formed.

[0165] For example, in the reflection electrode 216 f, a plurality ofthe notched parts 260 f′ cut from both the long sides and one of theshort sides of the reflection electrode 216 f and extending obliquely tothe long sides of the reflection electrode 216 f, are formed. In thereflection electrode 216 g, a plurality of the triangular notched parts260 g′ cut from both the long sides of the reflection electrode 216 gare formed. In the reflection electrode 216 h, a plurality of thewedge-like notched parts 260 h′ cut from both the long sides of thereflection electrode 216 h and extending in parallel to the short sidesof the reflection electrode 216 h are mutually adjacently formed. In thereflection electrode 216 i, a plurality of the hexagonal opening parts260 i and a plurality of the hexagonal notched parts 260 i′ cut fromboth the long sides of the reflection electrode 216 i, are formed. Inthe reflection electrode 216 j, a plurality of the slit-shaped notchedparts 260 j′ cut from the short sides of the reflection electrode 216 jand extending almost in parallel to the long sides of the reflectionelectrode 216 j, are formed. In the reflection electrode 216 k, aplurality of the slit-shaped notched parts 260 k′ cut from both the longsides of the reflection electrode 216 k and extending almost in parallelto the short sides of the reflection electrode 216 k, are formed. Tipend portions of the notched parts 260 k′ are formed into arcuateroundness.

[0166] The regions where the reflection electrodes 216 f to 216 k areformed serve as reflection regions. The regions where the opening parts260 i are formed, the regions where the notched parts 260 f′ to 260 k′of the peripheral parts of the reflection electrodes 216 f to 216 k areformed, and the regions around the reflection electrodes 216 f to 216 k,serve as transmission regions. According to this modified example, goodtransmission characteristics can be obtained compared with theconventional transflective type liquid crystal display device shown inFIG. 5.

[0167] The present invention is not limited to the above-describedfourth to fifth embodiments and can be variously modified.

[0168] For example, in the above embodiments, the bottom gate typesubstrate for a liquid crystal display device was exemplified. However,the present invention is not limited thereto and applicable also to atop gate type substrate for a liquid crystal display device.

[0169] Moreover, in the above fourth to fifth embodiments, the channelprotection film type substrate for a liquid crystal display device wasexemplified. However, the present invention is not limited thereto andapplicable also to a channel etch type substrate for a liquid crystaldisplay device.

[0170] Further, in the above fourth to fifth embodiments, the activematrix type liquid crystal display device was exemplified. However, thepresent invention is not limited thereto and applicable also to a simplematrix type liquid crystal display device.

[0171] Furthermore, in the above fourth to fifth embodiments, the liquidcrystal display device having the CF layers formed on the countersubstrate 204 opposingly arranged to the TFT substrate 202, wasexemplified. However, the present invention is not limited thereto andapplicable also to a liquid crystal display device having a so-calledCF-on-TFT structure, in which the CF layers are formed on the TFTsubstrate 202.

[0172] Further, in the above fourth to fifth embodiments, the liquidcrystal display device of VA mode was exemplified. However, the presentinvention is not limited thereto and applicable also to other liquidcrystal display devices of MVA (Multi-domain Vertical Alignment) mode,TN mode, HAN mode and the like.

[0173] In addition, in the above fourth to fifth embodiments, the CFlayers were exemplified as wavelength selecting layers. However, thepresent invention is not limited thereto, and a cholesteric liquidcrystal or the like in which the light of a specific wavelength isselectively reflected, may be used as a wavelength selecting layer.

[0174] The present invention is applicable to a MVA (Multi-domainVertical Alignment) type liquid crystal display. In this case, a slitfunctions as a structure for a multi-domain. When voltage is impressed,the liquid crystal molecules of the both side of a slit incline in thedifferent direction. Thereby, a multi-domain is attained. It is notnecessary. to rubbing, which can simplify the fabrication process.

What is claimed is:
 1. A liquid crystal display device constituted byenclosing liquid crystal between a pair of substrates, comprising: onone of the pair of substrates, gate bus lines supplied with scanningsignals; data bus lines supplied with display signals; thin-filmtransistors having gate electrodes electrically connected to the gatebus lines and drain electrodes electrically connected to the data buslines; a resin film divided for each picture element and havingwrinkle-form surface ruggedness; and reflection electrodes formed on theresin film, having ruggedness following the ruggedness of the resinfilm, and electrically connected to source electrodes of the thin-filmtransistors.
 2. The liquid crystal display device according to claim 1,wherein the resin film is partially divided for each picture element. 3.The liquid crystal display device according to claim 1, wherein theresin film and the reflection electrode are divided into a plurality ofregions by a slit.
 4. The liquid crystal display device according toclaim 1, wherein the gate bus lines, the data bus lines, and thethin-film transistors are disposed below the reflection electrodes, andregions without reflection electrodes serve as light transmissionregions.
 5. A liquid crystal display device constituted by enclosingliquid crystal between a pair of substrates, comprising: on one of thepair of substrates, gate bus lines supplied with scanning signals; databus lines supplied with display signals; thin-film transistors havinggate electrodes electrically connected to the gate bus lines and drainelectrodes electrically connected to the data bus lines; a resin filmdivided for each picture element and disposed on upper part of the gatebus lines, the data bus lines, and the thin-film transistors; andreflection electrodes formed on the resin film and electricallyconnected to source electrodes of the thin-film transistors.
 6. Theliquid crystal display device according to claim 5, wherein regionswithout reflection electrodes serve as light transmission regions. 7.The liquid crystal display device according to claim 5, wherein theresin film is formed of a positive type photoresist.
 8. The liquidcrystal display device according to claim 5, wherein the resin film ispartially divided for each picture element.
 9. A manufacturing methodfor a liquid crystal display device comprising the steps of: forming ona first substrate gate bus lines supplied with scanning signals, databus lines supplied with display signals, thin-film transistors havinggate electrodes connected to the gate bus lines and drain electrodesconnected to the data bus lines; forming a photoresist film on upperpart of the gate bus lines, the data bus lines, and the thin-filmtransistors; dividing the photoresist film for each picture element andexposing and developing photoresist to form opening parts at positionscorresponding to source electrodes of the thin-film transistors;changing inner stresses in a thickness direction of the photoresistfilm; subjecting the photoresist film to heat treatment to formwrinkle-form surface ruggedness; forming on the photoresist filmreflection electrodes electrically connected to the source electrodes ofthe thin-film transistors via the opening parts; and arrangingopposingly the first substrate and a second substrate provided with anelectrode made of a transparent conductive film, and enclosing liquidcrystal therebetween.
 10. The manufacturing method for the liquidcrystal display device according to claim 9, wherein the reflectionelectrodes are formed at positions overlapping with the gate bus lines,the data bus lines, and the thin-film transistors.
 11. The manufacturingmethod for the liquid crystal display device according to claim 9,wherein in the step of exposing and developing, a slit is formed so asto further dividing the resist film of one picture element into aplurality of regions, and in the step of forming the reflectionelectrodes, a part corresponding to the slit is opened to serve as alight transmission region.
 12. The manufacturing method for the liquidcrystal display device according to claim 9, wherein a structure formulti-domain is formed at least on one of the substrates.
 13. Amanufacturing method for a liquid crystal display device comprising thesteps of: forming on a first substrate gate bus lines supplied withscanning signals, data bus lines supplied with display signals,thin-film transistors having gate electrodes connected to the gate buslines and drain electrodes connected to the data bus lines; forming aphotoresist film on upper part of the gate bus lines, the data buslines, and the thin-film transistors; dividing the photoresist film foreach reflection electrode forming region overlapping with the gate buslines, the data bus lines, and the thin-film transistors, and exposingand developing photoresist to form opening parts at positionscorresponding to source electrodes of the thin-film transistors; formingon the photoresist film reflection electrodes electrically connected tothe source electrodes of the thin-film transistors via the openingparts; and arranging opposingly the first substrate and a secondsubstrate provided with an electrode made of a transparent conductivefilm, and enclosing liquid crystal therebetween.
 14. The liquid crystaldisplay device according to claim 13, wherein regions without reflectionelectrodes are set as light transmission regions.
 15. The manufacturingmethod for the liquid crystal display device according to claim 13,wherein a structure for multi-domain is formed at least on one of thesubstrates.
 16. A liquid crystal display device, comprising: a pair ofsubstrates opposingly arranged; a liquid crystal enclosed between thepair of substrates; a plurality of picture element regions, eachincluding a reflection region having a reflection electrode formed onone of the pair of substrates and reflecting light incident from a sideof the other substrate, and a transmission region transmitting lightincident from a side of the one substrate, the transmission region beinga region of a circumference or an opening part of the reflectionelectrode; and wavelength selecting layers, each formed in thetransmission region, extending up to part of the reflection region, andselecting and transmitting light having a predetermined wavelength. 17.The liquid crystal display device according to claim 16, furthercomprising second wavelength selecting layers, each formed in thetransmission region on the wavelength selecting layer and extending upto a part or whole of the transparent region.
 18. The liquid crystaldisplay device according to claim 17, wherein the wavelength selectinglayers and the second wavelength selecting layers transmit lights havingdifferent wavelengths from each other.
 19. The liquid crystal displaydevice according to claim 16, wherein the wavelength selecting layersare color filter layers obtained by mixing a pigment or a dye with atransparent resin.
 20. The liquid crystal display device according toclaim 16, further comprising a flattening film formed on the wavelengthselecting layers to flatten a surface of the substrate.
 21. The liquidcrystal display device according to claim 16, wherein the transmissionregion has a cell thickness thicker than a cell thickness in thereflection region.
 22. The liquid crystal display device according toclaim 21, wherein the transmission region has the cell thickness nearlytwice the cell thickness in the reflection region.
 23. The liquidcrystal display device according to claim 16, wherein the reflectionelectrodes are formed at positions overlapping with the gate bus lines,the data bus lines, and the thin-film transistors.
 24. The manufacturingmethod for the liquid crystal display device according to claim 16,wherein a structure for multi-domain is formed at least on one of thesubstrates.